Hole transport polymers

ABSTRACT

There is provided a polymer made from a monomer having Formula I:  
                 
where: 
 
R and Y are independently selected from the group consisting of H, D, alkyl, fluoroalkyl, aryl, fluoroaryl, alkoxy, aryloxy, NR″2, R′,  
                 
R′ is a crosslinkable group; R″ is independently selected from the group consisting of H, alkyl, fluoroalkyl, aryl, fluoroaryl, and R′; X is a leaving group; Z is C, Si, or N; 
         Q is (ZR″ n ) b ; a is an integer from 0 to 5; b is an integer from 0 to 20; c is an integer from 0 to 4; q is an integer from 0 to 7; and n is an integer from 1 to 2.

BACKGROUND INFORMATION

1. Field of the Disclosure

The present invention relates to novel compounds useful as holetransport materials in making electronic devices. The invention furtherrelates to electronic devices having at least one active layercomprising such a hole transport compound.

2. Description of the Related Art

In organic photoactive electronic devices, such as organic lightemitting diodes (“OLED”), that make up OLED displays, the organic activelayer is sandwiched between two electrical contact layers in an OLEDdisplay. In an OLED the organic photoactive layer emits light throughthe light-transmitting electrical contact layer upon application of avoltage across the electrical contact layers.

It is well known to use organic electroluminescent compounds as theactive component in light-emitting diodes. Simple organic molecules,conjugated polymers, and organometallic complexes have been used.Devices that use photoactive materials frequently include one or morecharge transport layers, which are positioned between a photoactive(e.g., light-emitting) layer and a contact layer (hole-injecting contactlayer). A device can contain two or more contact layers. A holetransport layer can be positioned between the photoactive layer and thehole-injecting contact layer. The hole-injecting contact layer may alsobe called the anode. An electron transport layer can be positionedbetween the photoactive layer and the electron-injecting contact layer.The electron-injecting contact layer may also be called the cathode.

There is a continuing need for charge transport materials for use inelectronic devices.

SUMMARY

There is provided a polymer made from at least one monomer havingFormula I:

where:

-   -   R and Y are independently selected from the group consisting of        H, D, alkyl, fluoroalkyl, aryl, fluoroaryl, alkoxy, aryloxy,        NR″2, R′,    -   R′ is a crosslinkable group;    -   R″ is independently selected from the group consisting of H,        alkyl, fluoroalkyl, aryl, fluoroaryl, and R′;    -   X can be the same or different at each occurrence and is a        leaving group;    -   Z is C, Si, or N;    -   Q is (ZR″_(n))_(b);    -   a is an integer from 0 to 5;    -   b is an integer from 0 to 20;    -   c is an integer from 0 to 4; and    -   q is an integer from 0 to 7.    -   n is an integer from 1 to 2

There is also provided a polymer comprising at least one copolymer madefrom a monomer having Formula I and at least one comonomer selected fromthe group consisting of Formulae II through VIII:

where:

-   -   R and Y are independently selected from the group consisting of        H, D, alkyl, fluoroalkyl, aryl, fluoroaryl, alkoxy, aryloxy,        NR″₂, R′,    -   R′ is a crosslinkable group;    -   R″ is independently selected from the group consisting of H,        alkyl, fluoroalkyl, aryl, fluoroaryl, and R′;    -   Q is (ZR″_(n))_(b);    -   X can be the same or different at each occurrence and is a        leaving group;    -   Z is C, Si, or N;    -   E is (ZR″_(n))_(b), O, S, Se, or Te;    -   a is an integer from 0 to 5;    -   b is an integer from 0 to 20;    -   c is an integer from 0 to 4;    -   q is an integer from 0 to 7, and    -   n is an integer from 1 to 2.

There is also provided an electronic device made with the polymer orcopolymer.

There is also provided a semiconductor made with the polymer orcopolymer.

The foregoing general description and the following detailed descriptionare exemplary and explanatory only and are not restrictive of theinvention, as defined in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments are illustrated in the accompanying figures to improveunderstanding of concepts as presented herein.

FIG. 1 includes as illustration of one example of an organic electronicdevice.

Skilled artisans appreciate that objects in the figures are illustratedfor simplicity and clarity and have not necessarily been drawn to scale.For example, the dimensions of some of the objects in the figures may beexaggerated relative to other objects to help to improve understandingof embodiments.

DETAILED DESCRIPTION

Many aspects and embodiments are disclosed herein and are exemplary andnot limiting. After reading this specification, skilled artisansappreciate that other aspects and embodiments are possible withoutdeparting from the scope of the invention.

Other features and benefits of any one or more of the embodiments willbe apparent from the following detailed description, and from theclaims. The detailed description first addresses Definitions andClarification of Terms followed by the Monomer, the Polymers, theElectronic Device, and finally Examples.

1. Definitions and Clarification of Terms

Before addressing details of embodiments described below, some terms aredefined or clarified.

As used herein, the term “alkyl” includes both branched andstraight-chain saturated aliphatic hydrocarbon groups. Unless otherwiseindicated, the term is also intended to include cyclic groups. Examplesof alkyl groups include methyl, ethyl, propyl, isopropyl, isobutyl,secbutyl, tertbutyl, pentyl, isopentyl, neopentyl, cyclopentyl, hexyl,cyclohexyl, isohexyl and the like. The term “alkyl” further includesboth substituted and unsubstituted hydrocarbon groups. In someembodiments, the alkyl group may be mono-, di- and tri-substituted. Oneexample of a substituted alkyl group is trifluoromethyl. Othersubstituted alkyl groups are formed from one or more of the substituentsdescribed herein. In certain embodiments alkyl groups have 1 to 20carbon atoms. In other embodiments, the group has 1 to 6 carbon atoms.The term is intended to include heteroalkyl groups. Heteroalkyl groupsmay have from 1-20 carbon atoms.

The term “aryl” means an aromatic carbocyclic moiety of up to 30 carbonatoms, which may be a single ring (monocyclic) or multiple rings(bicyclic, up to three rings) fused together or linked covalently. Anysuitable ring position of the aryl moiety may be covalently linked tothe defined chemical structure. Examples of aryl moieties include, butare not limited to, phenyl, 1-naphthyl, 2-naphthyl, dihydronaphthyl,tetrahydronaphthyl, biphenyl. anthryl, phenanthryl, fluorenyl, indanyl,biphenylenyl, acenaphthenyl, acenaphthylenyl, and the like. In someembodiments, aryl groups have 6 to 30 carbon atoms. The term is intendedto include heteroaryl groups. Heteroaryl groups may have from 4-30carbon atoms.

The term “alkoxy” is intended to mean the group —OR, where R is alkyl.

The term “aryloxy” is intended to mean the group —OR, where R is aryl.

Unless otherwise indicated, all groups can be substituted orunsubstituted.

An optionally substituted group, such as, but not limited to, alkyl oraryl, may be substituted with one or more substituents which may be thesame or different. Suitable substituents include alkyl, aryl, nitro,cyano, —N(R⁷)(R⁸), halo, hydroxy, carboxy, alkenyl, alkynyl, cycloalkyl,heteroaryl, alkoxy, aryloxy, heteroaryloxy, alkoxycarbonyl,perfluoroalkyl, perfluoroalkoxy, arylalkyl, thioalkoxy,—S(O)₂—N(R′)(R″), —C(═O)—N(R′)(R″), (R′)(R″)N-alkyl,(R′)(R″)N-alkoxyalkyl, (R′)(R″)N-alkylaryloxyalkyl, —S(O)_(s)-aryl(where s=0−2) or —S(O)_(s)-heteroaryl (where s=0−2). Each R′ and R″ isindependently an optionally substituted alkyl, cycloalkyl, or arylgroup. R′ and R″, together with the nitrogen atom to which they arebound, can form a ring system in certain embodiments.

The prefix “hetero” indicates that one or more carbon atoms has beenreplaced with a different atom. In some embodiments, the heteroatom isO, N, S, or combinations thereof.

The prefix “fluoro” is intended to indicate that one or more hydrogensin a group has been replaced with fluorine.

The term “photoactive” is intended to mean to any material that exhibitselectroluminescence or photosensitivity.

The term “polymer” is intended to include oligomers, homopolymers, andcopolymers having two or more different repeating units. A polymerhaving repeating units derived from a monomer “X-T-X” will haverepeating units

T

. “Polymer” may therefore also include polymers comprising comonomers ofthe same backbone but with different substituent groups.

The term “crosslinkable group” is intended to mean a group than can leadto crosslinking via thermal treatment or exposure to UV or visibleradiation.

The term “leaving group” is intended to mean a group that facilitatespolymerization and is eliminated in the polymerization reaction. In oneembodiment, the leaving group is a halide or boronic ester or boronicacid or triflate, where triflate is trifluoromethanesulfonate.

The phrase “adjacent to,” when used to refer to layers in a device, doesnot necessarily mean that one layer is immediately next to anotherlayer. On the other hand, the phrase “adjacent R groups,” is used torefer to R groups that are next to each other in a chemical formula(i.e., R groups that are on atoms joined by a bond).

The term “compound” is intended to mean an electrically unchargedsubstance made up of molecules that further consist of atoms, whereinthe atoms cannot be separated by physical means.

In addition, the IUPAC numbering system is used throughout, (CRCHandbook of Chemistry and Physics, 81^(st) Edition, 2000).

As used herein, the terms “comprises,” “comprising,” “includes,”“including,” “has,” “having” or any other variation thereof, areintended to cover a non-exclusive inclusion. For example, a process,method, article, or apparatus that comprises a list of elements is notnecessarily limited to only those elements but may include otherelements not expressly listed or inherent to such process, method,article, or apparatus. Further, unless expressly stated to the contrary,“or” refers to an inclusive or and not to an exclusive or. For example,a condition A or B is satisfied by any one of the following: A is true(or present) and B is false (or not present), A is false (or notpresent) and B is true (or present), and both A and B are true (orpresent).

Also, use of “a” or “an” are employed to describe elements andcomponents described herein. This is done merely for convenience and togive a general sense of the scope of the invention. This descriptionshould be read to include one or at least one and the singular alsoincludes the plural unless it is obvious that it is meant otherwise.

Group numbers corresponding to columns within the Periodic Table of theelements use the “New Notation” convention as seen in the CRC Handbookof Chemistry and Physics, 81^(st) Edition (2000-2001), where the groupsare numbered from left to right as 1 through 18.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although methods and materialssimilar or equivalent to those described herein can be used in thepractice or testing of embodiments of the present invention, suitablemethods and materials are described below. All publications, patentapplications, patents, and other references mentioned herein areincorporated by reference in their entirety, unless a particular passageis cited. In case of conflict, the present specification, includingdefinitions, will control. In addition, the materials, methods, andexamples are illustrative only and not intended to be limiting.

Some details regarding specific materials, processing acts, and circuitsare conventional and may be found in textbooks and other sources withinthe organic light-emitting diode display, photodetector, photovoltaic,and semiconductive member arts and therefore need not be presentedherein for a fully enabling disclosure.

2. Monomer

The monomer having Formula I

has a central fluorenyl group (or the silyl or the carbazole analog)with arylamine end groups.

In one embodiment, Y is alkyl. In one embodiment, the alkyl groups havefrom 1-10 carbon atoms.

In one embodiment, R is aryl. In one embodiment, R is phenyl.

The X group is the leaving group that is eliminated in thepolymerization reaction. Any effective leaving group can be used,including chloride, bromide, and triflate leaving groups. In oneembodiment, X═Br.

3. Polymers

Homopolymers of monomers having Formula I can be made by Yamamotopolymerization. In this synthetic method, as described in Yamamoto,Progress in Polymer Science, Vol. 17, p 1153 (1992), the monomers havingtwo leaving groups are reacted with a stoichiometric amount of azerovalent nickel compound, such as bis(1,5-cyclooctadiene)nickel(0).Such homopolymers will have exclusively arylamine end groups.

In one embodiment, the homopolymer has Formula IX:

This polymer is different from one made by the copolymerization of

by Suzuki coupling (as described in U.S. Pat. No. 5,962,631, andpublished PCT application WO 00/53565). The Suzuki polymer will havesome fluorene end groups, whereas the homopolymer of Formula VIII willonly have triarylamine end groups.

In some embodiment, the monomer having Formula I is reacted with one ormore comonomers to form a copolymer. In one embodiment, the copolymer isformed by Yamamoto polymerization. Surprisingly, it has been found thatin some embodiments, the copolymers of monomers with Formula I that areformed by Yamamoto polymerization have improved properties in electronicdevices. In some embodiments, electronic devices made with the Yamamotocopolymers, exhibit longer lifetimes.

In some embodiments, copolymers are made from comonomers having FormulaeII through VII:

where:

-   -   R and Y are independently selected from the group consisting of        H, D, alkyl, fluoroalkyl, aryl, fluoroaryl, alkoxy, aryloxy,        NR″₂, R′,    -   R′ is a crosslinkable group;    -   R″ is independently selected from the group consisting of H,        alkyl, fluoroalkyl, aryl, fluoroaryl, and R′;    -   Q is (ZR″_(n))_(b);    -   X is a leaving group;    -   Z is C, Si, or N;    -   E is (ZR″_(n))_(b), O, S, Se, or Te;    -   a is an integer from 0 to 5;    -   b is an integer from 0 to 20;    -   c is an integer from 0 to 4;    -   q is an integer from 0 to 7, and    -   n is an integer from 1 to 2.

When R′ is present, the copolymer will be crosslinkable. The copolymercan be formed into a film and then crosslinked by exposure to heatand/or radiation to form a more robust, less soluble film. In someembodiments, the uncrosslinked polymer is soluble in solvents for filmforming, and the crosslinked film is not soluble and thus is undisturbedby solvents used in later processing steps.

Examples of R′ groups include, but are not limited to vinyl, acrylate,perfluorovinylether, 1-benzo-3,4-cyclobutane, siloxane, and methylesters. In one embodiment, R′ is vinyl.

In one embodiment, the copolymer has a formula selected from Formulae Xthrough XII:

4. Electronic Devices

Organic electronic devices that may benefit from having one or morelayers comprising at least one compound as described herein include, butare not limited to, (1) devices that convert electrical energy intoradiation (e.g., a light-emitting diode, light emitting diode display,or diode laser), (2) devices that detect signals through electronicsprocesses (e.g., photodetectors, photoconductive cells, photoresistors,photoswitches, phototransistors, phototubes, IR detectors), (3) devicesthat convert radiation into electrical energy, (e.g., a photovoltaicdevice or solar cell), and (4) devices that include one or moreelectronic components that include one or more organic semi-conductorlayers (e.g., a transistor or diode). Other uses for the compositionsaccording to the present invention include coating materials for memorystorage devices, antistatic films, biosensors, electrochromic devices,solid electrolyte capacitors, energy storage devices such as arechargeable battery, and electromagnetic shielding applications.

One illustration of an organic electronic device structure is shown inFIG. 1. The device 100 has an anode layer 110 and a cathode layer 150,and a photoactive layer 130 between them. Adjacent to the anode is alayer 120 comprising a charge transport layer, for example, a holetransport material. Adjacent to the cathode may be a charge transportlayer 140 comprising an electron transport material. As an option,devices may use one or more additional hole injection or hole transportlayers (not shown) next to the anode 110 and/or one or more additionalelectron injection or electron transport layers (not shown) next to thecathode 150.

As used herein, the term “photoactive” refers to a material that emitslight when activated by an applied voltage (such as in a light-emittingdiode or light-emitting electrochemical cell), or responds to radiantenergy and generates a signal with or without an applied bias voltage(such as in a photodetector). In one embodiment, a photoactive layer isan emitter layer.

As used herein, the term “charge transport,” when referring to a layeror material is intended to mean such layer or material facilitatesmigration of such charge through the thickness of such layer, material,member, or structure with relative efficiency and small loss of charge,and is meant to be broad enough to include materials that may act as ahole transport or an electron transport material. The term “electrontransport” when referring to a layer or material means such a layer ormaterial, member or structure that promotes or facilitates migration ofelectrons through such a layer or material into another layer, material,member or structure.

Depending upon the application of the device 100, the photoactive layer130 can be a light-emitting layer that is activated by an appliedvoltage (such as in a light-emitting diode or light-emittingelectrochemical cell), a layer of material that responds to radiantenergy and generates a signal with or without an applied bias voltage(such as in a photodetector). Examples of photodetectors includephotoconductive cells, photoresistors, photoswitches, phototransistors,and phototubes, and photovoltaic cells, as these terms are described inKirk-Othmer Concise Encyclopedia of Chemical Technology, 4^(th) edition,p. 1537, (1999).

In some embodiments, the hole transport layer 120 comprises at least onenew polymer as described herein. In some embodiments, the device furthercomprises a buffer layer between the anode and the layer comprising thenew polymer. The term “buffer layer” is intended to mean a layercomprising electrically conductive or semiconductive materials and mayhave one or more functions in an organic electronic device, includingbut not limited to, planarization of the underlying layer, chargetransport and/or charge injection properties, scavenging of impuritiessuch as oxygen or metal ions, and other aspects to facilitate or toimprove the performance of the organic electronic device. Buffermaterials may be polymers, oligomers, or small molecules, and may be inthe form of solutions, dispersions, suspensions, emulsions, colloidalmixtures, or other compositions.

In some embodiment, the device further comprises an additional holetransport layer between the photoactive layer and the layer comprisingthe new polymer.

In some embodiments, the photoactive layer comprises at least onephotoactive material and at least one new polymer as described herein.The new polymer functions as a host for the photoactive material.

The other layers in the device can be made of any materials which areknown to be useful in such layers. The anode 110, is an electrode thatis particularly efficient for injecting positive charge carriers. It canbe made of, for example materials containing a metal, mixed metal,alloy, metal oxide or mixed-metal oxide, or it can be a conductingpolymer, and mixtures thereof. Suitable metals include the Group 11metals, the metals in Groups 4, 5, and 6, and the Group 8 10 transitionmetals. If the anode is to be light-transmitting, mixed-metal oxides ofGroups 12, 13 and 14 metals, such as indium-tin-oxide, are generallyused. The anode 110 may also comprise an organic material such aspolyaniline as described in “Flexible light-emitting diodes made fromsoluble conducting polymer,” Nature vol. 357, pp 477 479 (11 Jun. 1992).At least one of the anode and cathode should be at least partiallytransparent to allow the generated light to be observed.

The hole transport layer, which is a layer that facilitates themigration of negative charges through the layer into another layer ofthe electronic device, can include any number of materials. Examples ofother hole transport materials for layer 120 have been summarized forexample, in Kirk Othmer Encyclopedia of Chemical Technology, FourthEdition, Vol. 18, p. 837 860, 1996, by Y. Wang. Both hole transportingmolecules and polymers can be used. Commonly used hole transportingmolecules include, but are not limited to:N,N′-diphenyl-N,N′-bis(3-methylphenyl)-[1,1′-biphenyl]-4,4′-diamine(TPD), 1,1-bis[(di-4-tolylamino) phenyl]cyclohexane (TAPC),N,N′-bis(4-methylphenyl)-N,N′-bis(4-ethylphenyl)-[1,1′-(3,3′-dimethyl)biphenyl]-4,4′-diamine(ETPD), tetrakis (3-methylphenyl)-N,N,N′,N′-2,5-phenylenediamine (PDA),a-phenyl 4-N,N-diphenylaminostyrene (TPS), p-(diethylamino)benzaldehydediphenylhydrazone (DEH), triphenylamine (TPA), bis[4(N,N-diethylamino)-2-methylphenyl](4-methylphenyl)methane (MPMP),1-phenyl-3-[p-(diethylamino)styryl]-5-[p-(diethylamino)phenyl]pyrazoline(PPR or DEASP), 1,2-trans-bis(9H-carbazol-9-yl)cyclobutane (DCZB),N,N,N′,N′tetrakis(4-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine (TTB),N,N′-Bis(naphthalen-1-yl)-N,N′-bis-(phenyl)benzidine (α-NPB), andporphyrinic compounds, such as copper phthalocyanine. Commonly used holetransporting polymers include, but are not limited to,polyvinylcarbazole, (phenylmethyl)polysilane, and polyaniline. It isalso possible to obtain hole transporting polymers by doping holetransporting molecules such as those mentioned above into polymers suchas polystyrene and polycarbonate. Buffer layers and/or hole transportlayer can also comprise polymers of thiophene, aniline, or pyrrole withpolymeric fluorinated sulfonic acids, as described in published USapplications 2004/102577, 2004/127637, and 2005/205860.

Any organic electroluminescent (“EL”) material can be used as thephotoactive material in layer 130. Such materials include, but are notlimited to, one of more compounds of the instant invention, smallorganic fluorescent compounds, fluorescent and phosphorescent metalcomplexes, conjugated polymers, and mixtures thereof. Examples offluorescent compounds include, but are not limited to, pyrene, perylene,rubrene, coumarin, derivatives thereof, and mixtures thereof. Examplesof metal complexes include, but are not limited to, metal chelatedoxinoid compounds, such as tris(8-hydroxyquinolato)aluminum (Alq3);cyclometallated iridium and platinum electroluminescent compounds, andmixtures thereof. Examples of conjugated polymers include, but are notlimited to poly(phenylenevinylenes), polyfluorenes,poly(spirobifluorenes), polythiophenes, poly(p-phenylenes), copolymersthereof, and mixtures thereof. The materials may also be present inadmixture with a host material. In some embodiments, the host materialis a hole transport material or an electron transport material.

Examples of electron transport materials which can be used in theelectron transport layer 140 and/or the optional layer between layer 140and the cathode, include metal chelated oxinoid compounds, such astris(8-hydroxyquinolato)aluminum (Alq3) andtetrakis-(8-hydroxyquinolato)zirconium (Zrq4); and azole compounds suchas 2-(4-biphenylyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole (PBD),3-(4-biphenylyl)-4-phenyl-5-(4-t-butylphenyl)-1,2,4-triazole (TAZ), and1,3,5-tri(phenyl-2-benzimidazole)benzene (TPBI); quinoxaline derivativessuch as 2,3-bis(4-fluorophenyl)quinoxaline; phenanthrolines such as4,7-diphenyl-1,10-phenanthroline (DPA) and2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (DDPA); and mixturesthereof.

The cathode 150, is an electrode that is particularly efficient forinjecting electrons or negative charge carriers. The cathode can be anymetal or nonmetal having a lower work function than the anode. Materialsfor the cathode can be selected from alkali metals of Group 1 (e.g., Li,Cs), the Group 2 (alkaline earth) metals, the Group 12 metals, includingthe rare earth elements and lanthanides, and the actinides. Materialssuch as aluminum, indium, calcium, barium, samarium and magnesium, aswell as combinations, can be used. Li-containing organometalliccompounds, LiF, and Li₂O can also be deposited between the organic layerand the cathode layer to lower the operating voltage.

The choice of materials for each of the component layers is preferablydetermined by balancing the goals of providing a device with high deviceefficiency with device operational lifetime.

The device can be prepared by a variety of techniques, includingsequentially depositing the individual layers on a suitable substrate.Substrates such as glass and polymeric films can be used. Conventionalvapor deposition techniques can be used, such as thermal evaporation,chemical vapor deposition, and the like. Alternatively, the organiclayers can be applied by liquid deposition using suitable solvents. Theliquid can be in the form of solutions, dispersions, or emulsions.Typical liquid deposition techniques include, but are not limited to,continuous deposition techniques such as spin coating, gravure coating,curtain coating, dip coating, slot-die coating, spray-coating, andcontinuous nozzle coating; and discontinuous deposition techniques suchas ink jet printing, gravure printing, and screen printing anyconventional coating or printing technique, including but not limited tospin-coating, dip-coating, roll-to-roll techniques, ink jet printing,screen-printing, gravure printing and the like.

The new polymers described herein can be applied by liquid depositionfrom a liquid composition. The term “liquid composition” is intended tomean a liquid medium in which a material is dissolved to form asolution, a liquid medium in which a material is dispersed to form adispersion, or a liquid medium in which a material is suspended to forma suspension or an emulsion.

In one embodiment, the different layers have the following range ofthicknesses: anode 110, 500-5000 Å, in one embodiment 1000-2000 Å; holetransport layer 120, 50-2000 Å, in one embodiment 200-1000 Å;photoactive layer 130, 10-2000 Å, in one embodiment 100-1000 Å; layer140, 50-2000 Å, in one embodiment 100-1000 Å; cathode 150, 200-10000 Å,in one embodiment 300-5000 Å. The location of the electron-holerecombination zone in the device, and thus the emission spectrum of thedevice, can be affected by the relative thickness of each layer. Thusthe thickness of the electron-transport layer should be chosen so thatthe electron-hole recombination zone is in the light-emitting layer. Thedesired ratio of layer thicknesses will depend on the exact nature ofthe materials used.

In one embodiment, the device has the following structure, in order:anode, buffer layer, hole transport layer, photoactive layer, electrontransport layer, electron injection layer, cathode. In one embodiment,the anode is made of indium tin oxide or indium zinc oxide. In oneembodiment, the buffer layer comprises a conducting polymer selectedfrom the group consisting of polythiophenes, polyanilines, polypyrroles,copolymers thereof, and mixtures thereof. In one embodiment, the bufferlayer comprises a complex of a conducting polymer and a colloid-formingpolymeric acid. In one embodiment, the buffer layer comprises a compoundhaving triarylamine or triarylmethane groups. In one embodiment, thebuffer layer comprises a material selected from the group consisting ofTPD, MPMP, NPB, CBP, and mixtures thereof, as defined above.

In one embodiment, the hole transport layer comprises polymeric holetransport material. In one embodiment, the hole transport layer iscrosslinkable. In one embodiment, the hole transport layer comprises acompound having triarylamine or triarylmethane groups. In oneembodiment, the buffer layer comprises a material selected from thegroup consisting of TPD, MPMP, NPB, CBP, and mixtures thereof, asdefined above.

In one embodiment, the photoactive layer comprises an electroluminescentmaterial and a host material. The host can be a charge transportmaterial. In one embodiment, the electroluminescent material is presentin an amount of at least 1% by weight. In one embodiment, theelectroluminescent material is 2-20% by weight. In one embodiment, theelectroluminescent material is 20-50% by weight. In one embodiment, theelectroluminescent material is 50-80% by weight. In one embodiment, theelectroluminescent material is 80-99% by weight. In one embodiment, theelectroluminescent material is metal complex. In one embodiment, themetal complex is a cyclometallated complex of iridium, platinum,rhenium, or osmium. In one embodiment, the photoactive layer furthercomprises a second host material. The second host can be a chargetransport material. In one embodiment, the second host is a holetransport material. In one embodiment, the second host is an electrontransport material. In one embodiment, the second host material is ametal complex of a hydroxyaryl-N-heterocycle. In one embodiment, thehydroxyaryl-N-heterocycle is unsubstituted or substituted8-hydroxyquinoline. In one embodiment, the metal is aluminum. In oneembodiment, the second host is a material selected from the groupconsisting of tris(8-hydroxyquinolinato)aluminum,bis(8-hydroxyquinolinato)(4-phenylphenolato)aluminum,tetrakis(8-hydroxyquinolinato)zirconium, and mixtures thereof. The ratioof the first host to the second host can be 1:100 to 100:1. In oneembodiment the ratio is from 1:10 to 10:1. In one embodiment, the ratiois from 1:10 to 1:5. In one embodiment, the ratio is from 1:5 to 1:1. Inone embodiment, the ratio is from 1:1 to 5:1. In one embodiment, theratio is from 5:1 to 5:10.

In one embodiment, the electron transport layer comprises a metalcomplex of a hydroxyaryl-N-heterocycle. In one embodiment, thehydroxyaryl-N-heterocycle is unsubstituted or substituted8-hydroxyquinoline. In one embodiment, the metal is aluminum. In oneembodiment, the electron transport layer comprises a material selectedfrom the group consisting of tris(8-hydroxyquinolinato)aluminum,bis(8-hydroxyquinolinato)(4-phenylphenolato)aluminum,tetrakis(8-hydroxyquinolinato)zirconium, and mixtures thereof. In oneembodiment, the electron injection layer is LiF or LiO₂. In oneembodiment, the cathode is Al or Ba/Al.

In one embodiment, the device is fabricated by liquid deposition of thebuffer layer, the hole transport layer, and the photoactive layer, andby vapor deposition of the electron transport layer, the electroninjection layer, and the cathode.

The buffer layer can be deposited from any liquid medium in which it isdissolved or dispersed and from which it will form a film. In oneembodiment, the liquid medium consists essentially of one or moreorganic solvents. In one embodiment, the liquid medium consistsessentially of water or water and an organic solvent. In one embodimentthe organic solvent is selected from the group consisting of alcohols,ketones, cyclic ethers, and polyols. In one embodiment, the organicliquid is selected from dimethylacetamide (“DMAc”), N-methylpyrrolidone(“NMP”), dimethylformamide (“DMF”), ethylene glycol (“EG”), aliphaticalcohols, and mixtures thereof. The buffer material can be present inthe liquid medium in an amount from 0.5 to 10 percent by weight. Otherweight percentages of buffer material may be used depending upon theliquid medium. The buffer layer can be applied by any continuous ordiscontinuous liquid deposition technique. In one embodiment, the bufferlayer is applied by spin coating. In one embodiment, the buffer layer isapplied by ink jet printing. After liquid deposition, the liquid mediumcan be removed in air, in an inert atmosphere, or by vacuum, at roomtemperature or with heating. In one embodiment, the layer is heated to atemperature less than 275° C. In one embodiment, the heating temperatureis between 100° C. and 275° C. In one embodiment, the heatingtemperature is between 100° C. and 120° C. In one embodiment, theheating temperature is between 120° C. and 140° C. In one embodiment,the heating temperature is between 140° C. and 160° C. In oneembodiment, the heating temperature is between 160° C. and 180° C. Inone embodiment, the heating temperature is between 180° C. and 200° C.In one embodiment, the heating temperature is between 200° C. and 220°C. In one embodiment, the heating temperature is between 190° C. and220° C. In one embodiment, the heating temperature is between 220° C.and 240° C. In one embodiment, the heating temperature is between 240°C. and 260° C. In one embodiment, the heating temperature is between260° C. and 275° C. The heating time is dependent upon the temperature,and is generally between 5 and 60 minutes. In one embodiment, the finallayer thickness is between 5 and 200 nm. In one embodiment, the finallayer thickness is between 5 and 40 nm. In one embodiment, the finallayer thickness is between 40 and 80 nm. In one embodiment, the finallayer thickness is between 80 and 120 nm. In one embodiment, the finallayer thickness is between 120 and 160 nm. In one embodiment, the finallayer thickness is between 160 and 200 nm.

The hole transport layer can be deposited from any liquid medium inwhich it is dissolved or dispersed and from which it will form a film.In one embodiment, the liquid medium consists essentially of one or moreorganic solvents. In one embodiment, the liquid medium consistsessentially of water or water and an organic solvent. In one embodimentthe organic solvent is an aromatic solvent. In one embodiment, theorganic liquid is selected from chloroform, dichloromethane, toluene,anisole, and mixtures thereof. The hole transport material can bepresent in the liquid medium in a concentration of 0.2 to 2 percent byweight. Other weight percentages of hole transport material may be useddepending upon the liquid medium. The hole transport layer can beapplied by any continuous or discontinuous liquid deposition technique.In one embodiment, the hole transport layer is applied by spin coating.In one embodiment, the hole transport layer is applied by ink jetprinting. After liquid deposition, the liquid medium can be removed inair, in an inert atmosphere, or by vacuum, at room temperature or withheating. In one embodiment, the layer is heated to a temperature of 300°C. or less. In one embodiment, the heating temperature is between 170°C. and 275° C. In one embodiment, the heating temperature is between170° C. and 200° C. In one embodiment, the heating temperature isbetween 190° C. and 220° C. In one embodiment, the heating temperatureis between 210° C. and 240° C. In one embodiment, the heatingtemperature is between 230° C. and 270° C. The heating time is dependentupon the temperature, and is generally between 5 and 60 minutes. In oneembodiment, the final layer thickness is between 5 and 50 nm. In oneembodiment, the final layer thickness is between 5 and 15 nm. In oneembodiment, the final layer thickness is between 15 and 25 nm. In oneembodiment, the final layer thickness is between 25 and 35 nm. In oneembodiment, the final layer thickness is between 35 and 50 nm.

The photoactive layer can be deposited from any liquid medium in whichit is dissolved or dispersed and from which it will form a film. In oneembodiment, the liquid medium consists essentially of one or moreorganic solvents. In one embodiment, the liquid medium consistsessentially of water or water and an organic solvent. In one embodimentthe organic solvent is an aromatic solvent. In one embodiment, theorganic liquid is selected from chloroform, dichloromethane, toluene,anisole, and mixtures thereof. The photoactive material can be presentin the liquid medium in a concentration of 0.2 to 2 percent by weight.Other weight percentages of photoactive material may be used dependingupon the liquid medium. The photoactive layer can be applied by anycontinuous or discontinuous liquid deposition technique. In oneembodiment, the photoactive layer is applied by spin coating. In oneembodiment, the photoactive layer is applied by ink jet printing. Afterliquid deposition, the liquid medium can be removed in air, in an inertatmosphere, or by vacuum, at room temperature or with heating. In oneembodiment, the deposited layer is heated to a temperature that is lessthan the Tg of the material having the lowest Tg. In one embodiment, theheating temperature is at least 10° C. less than the lowest Tg. In oneembodiment, the heating temperature is at least 20° C. less than thelowest Tg. In one embodiment, the heating temperature is at least 30° C.less than the lowest Tg. In one embodiment, the heating temperature isbetween 50° C. and 150° C. In one embodiment, the heating temperature isbetween 50° C. and 75° C. In one embodiment, the heating temperature isbetween 75° C. and 100° C. In one embodiment, the heating temperature isbetween 100° C. and 125° C. In one embodiment, the heating temperatureis between 125° C. and 150° C. The heating time is dependent upon thetemperature, and is generally between 5 and 60 minutes. In oneembodiment, the final layer thickness is between 25 and 100 nm. In oneembodiment, the final layer thickness is between 25 and 40 nm. In oneembodiment, the final layer thickness is between 40 and 65 nm. In oneembodiment, the final layer thickness is between 65 and 80 nm. In oneembodiment, the final layer thickness is between 80 and 100 nm.

The electron transport layer can be deposited by any vapor depositionmethod. In one embodiment, it is deposited by thermal evaporation undervacuum. In one embodiment, the final layer thickness is between 1 and100 nm. In one embodiment, the final layer thickness is between 1 and 15nm. In one embodiment, the final layer thickness is between 15 and 30nm. In one embodiment, the final layer thickness is between 30 and 45nm. In one embodiment, the final layer thickness is between 45 and 60nm. In one embodiment, the final layer thickness is between 60 and 75nm. In one embodiment, the final layer thickness is between 75 and 90nm. In one embodiment, the final layer thickness is between 90 and 100nm.

The electron injection layer can be deposited by any vapor depositionmethod. In one embodiment, it is deposited by thermal evaporation undervacuum. In one embodiment, the vacuum is less than 10⁻⁶ torr. In oneembodiment, the vacuum is less than 10⁻⁷ torr. In one embodiment, thevacuum is less than 10⁻⁸ torr. In one embodiment, the material is heatedto a temperature in the range of 100° C. to 400° C.; 150° C. to 350° C.preferably. All vapor deposition rates given herein are in units ofAngstroms per second. In one embodiment, the material is deposited at arate of 0.5 to 10 Å/sec. In one embodiment, the material is deposited ata rate of 0.5 to 1 Å/sec. In one embodiment, the material is depositedat a rate of 1 to 2 Å/sec. In one embodiment, the material is depositedat a rate of 2 to 3 Å/sec. In one embodiment, the material is depositedat a rate of 3 to 4 Å/sec. In one embodiment, the material is depositedat a rate of 4 to 5 Å/sec. In one embodiment, the material is depositedat a rate of 5 to 6 Å/sec. In one embodiment, the material is depositedat a rate of 6 to 7 Å/sec. In one embodiment, the material is depositedat a rate of 7 to 8 Å/sec. In one embodiment, the material is depositedat a rate of 8 to 9 Å/sec. In one embodiment, the material is depositedat a rate of 9 to 10 Å/sec. In one embodiment, the final layer thicknessis between 0.1 and 3 nm. In one embodiment, the final layer thickness isbetween 0.1 and 1 nm. In one embodiment, the final layer thickness isbetween 1 and 2 nm. In one embodiment, the final layer thickness isbetween 2 and 3 nm.

The cathode can be deposited by any vapor deposition method. In oneembodiment, it is deposited by thermal evaporation under vacuum. In oneembodiment, the vacuum is less than 10⁻⁶ torr. In one embodiment, thevacuum is less than 10⁻⁷ torr. In one embodiment, the vacuum is lessthan 10⁻⁸ torr. In one embodiment, the material is heated to atemperature in the range of 100° C. to 400° C.; 150° C. to 350° C.preferably. In one embodiment, the material is deposited at a rate of0.5 to 10 Å/sec. In one embodiment, the material is deposited at a rateof 0.5 to 1 Å/sec. In one embodiment, the material is deposited at arate of 1 to 2 Å/sec. In one embodiment, the material is deposited at arate of 2 to 3 Å/sec. In one embodiment, the material is deposited at arate of 3 to 4 Å/sec. In one embodiment, the material is deposited at arate of 4 to 5 Å/sec. In one embodiment, the material is deposited at arate of 5 to 6 Å/sec. In one embodiment, the material is deposited at arate of 6 to 7 Å/sec. In one embodiment, the material is deposited at arate of 7 to 8 Å/sec. In one embodiment, the material is deposited at arate of 8 to 9 Å/sec. In one embodiment, the material is deposited at arate of 9 to 10 Å/sec. In one embodiment, the final layer thickness isbetween 10 and 10000 nm. In one embodiment, the final layer thickness isbetween 10 and 1000 nm. In one embodiment, the final layer thickness isbetween 10 and 50 nm. In one embodiment, the final layer thickness isbetween 50 and 100 nm. In one embodiment, the final layer thickness isbetween 100 and 200 nm. In one embodiment, the final layer thickness isbetween 200 and 300 nm. In one embodiment, the final layer thickness isbetween 300 and 400 nm. In one embodiment, the final layer thickness isbetween 400 and 500 nm. In one embodiment, the final layer thickness isbetween 500 and 600 nm. In one embodiment, the final layer thickness isbetween 600 and 700 nm. In one embodiment, the final layer thickness isbetween 700 and 800 nm. In one embodiment, the final layer thickness isbetween 800 and 900 nm. In one embodiment, the final layer thickness isbetween 900 and 1000 nm. In one embodiment, the final layer thickness isbetween 1000 and 2000 nm. In one embodiment, the final layer thicknessis between 2000 and 3000 nm. In one embodiment, the final layerthickness is between 3000 and 4000 nm. In one embodiment, the finallayer thickness is between 4000 and 5000 nm. In one embodiment, thefinal layer thickness is between 5000 and 6000 nm. In one embodiment,the final layer thickness is between 6000 and 7000 nm. In oneembodiment, the final layer thickness is between 7000 and 8000 nm. Inone embodiment, the final layer thickness is between 8000 and 9000 nm.In one embodiment, the final layer thickness is between 9000 and 10000nm.

In one embodiment, the device is fabricated by vapor deposition of thebuffer layer, the hole transport layer, and the photoactive layer, theelectron transport layer, the electron injection layer, and the cathode.

In one embodiment, the buffer layer is applied by vapor deposition. Inone embodiment, it is deposited by thermal evaporation under vacuum. Inone embodiment, the vacuum is less than 10⁻⁶ torr. In one embodiment,the vacuum is less than 10⁻⁷ torr. In one embodiment, the vacuum is lessthan 10⁻⁸ torr. In one embodiment, the material is heated to atemperature in the range of 100° C. to 400° C.; 150° C. to 350° C.preferably. In one embodiment, the material is deposited at a rate of0.5 to 10 Å/sec. In one embodiment, the material is deposited at a rateof 0.5 to 1 Å/sec. In one embodiment, the material is deposited at arate of 1 to 2 Å/sec. In one embodiment, the material is deposited at arate of 2 to 3 Å/sec. In one embodiment, the material is deposited at arate of 3 to 4 Å/sec. In one embodiment, the material is deposited at arate of 4 to 5 Å/sec. In one embodiment, the material is deposited at arate of 5 to 6 Å/sec. In one embodiment, the material is deposited at arate of 6 to 7 Å/sec. In one embodiment, the material is deposited at arate of 7 to 8 Å/sec. In one embodiment, the material is deposited at arate of 8 to 9 Å/sec. In one embodiment, the material is deposited at arate of 9 to 10 Å/sec. In one embodiment, the final layer thickness isbetween 5 and 200 nm. In one embodiment, the final layer thickness isbetween 5 and 30 nm. In one embodiment, the final layer thickness isbetween 30 and 60 nm. In one embodiment, the final layer thickness isbetween 60 and 90 nm. In one embodiment, the final layer thickness isbetween 90 and 120 nm. In one embodiment, the final layer thickness isbetween 120 and 150 nm. In one embodiment, the final layer thickness isbetween 150 and 280 nm. In one embodiment, the final layer thickness isbetween 180 and 200 nm.

In one embodiment, the hole transport layer is applied by vapordeposition. In one embodiment, it is deposited by thermal evaporationunder vacuum. In one embodiment, the vacuum is less than 10⁻⁶ torr. Inone embodiment, the vacuum is less than 10⁻⁷ torr. In one embodiment,the vacuum is less than 10⁻⁸ torr. In one embodiment, the material isheated to a temperature in the range of 100° C. to 400° C.; 150° C. to350° C. preferably. In one embodiment, the material is deposited at arate of 0.5 to 10 Å/sec. In one embodiment, the material is deposited ata rate of 0.5 to 1 Å/sec. In one embodiment, the material is depositedat a rate of 1 to 2 Å/sec. In one embodiment, the material is depositedat a rate of 2 to 3 Å/sec. In one embodiment, the material is depositedat a rate of 3 to 4 Å/sec. In one embodiment, the material is depositedat a rate of 4 to 5 Å/sec. In one embodiment, the material is depositedat a rate of 5 to 6 Å/sec. In one embodiment, the material is depositedat a rate of 6 to 7 Å/sec. In one embodiment, the material is depositedat a rate of 7 to 8 Å/sec. In one embodiment, the material is depositedat a rate of 8 to 9 Å/sec. In one embodiment, the material is depositedat a rate of 9 to 10 Å/sec. In one embodiment, the final layer thicknessis between 5 and 200 nm. In one embodiment, the final layer thickness isbetween 5 and 30 nm. In one embodiment, the final layer thickness isbetween 30 and 60 nm. In one embodiment, the final layer thickness isbetween 60 and 90 nm. In one embodiment, the final layer thickness isbetween 90 and 120 nm. In one embodiment, the final layer thickness isbetween 120 and 150 nm. In one embodiment, the final layer thickness isbetween 150 and 280 nm. In one embodiment, the final layer thickness isbetween 180 and 200 nm.

In one embodiment, the photoactive layer is applied by vapor deposition.In one embodiment, it is deposited by thermal evaporation under vacuum.In one embodiment, the photoactive layer consists essentially of asingle electroluminescent compound, which is deposited by thermalevaporation under vacuum. In one embodiment, the vacuum is less than10⁻⁶ torr. In one embodiment, the vacuum is less than 10⁻⁷ torr. In oneembodiment, the vacuum is less than 10⁻⁸ torr. In one embodiment, thematerial is heated to a temperature in the range of 100° C. to 400° C.;150° C. to 350° C. preferably. In one embodiment, the material isdeposited at a rate of 0.5 to 10 Å/sec. In one embodiment, the materialis deposited at a rate of 0.5 to 1 Å/sec. In one embodiment, thematerial is deposited at a rate of 1 to 2 Å/sec. In one embodiment, thematerial is deposited at a rate of 2 to 3 Å/sec. In one embodiment, thematerial is deposited at a rate of 3 to 4 Å/sec. In one embodiment, thematerial is deposited at a rate of 4 to 5 Å/sec. In one embodiment, thematerial is deposited at a rate of 5 to 6 Å/sec. In one embodiment, thematerial is deposited at a rate of 6 to 7 Å/sec. In one embodiment, thematerial is deposited at a rate of 7 to 8 Å/sec. In one embodiment, thematerial is deposited at a rate of 8 to 9 Å/sec. In one embodiment, thematerial is deposited at a rate of 9 to 10 Å/sec. In one embodiment, thefinal layer thickness is between 5 and 200 nm. In one embodiment, thefinal layer thickness is between 5 and 30 nm. In one embodiment, thefinal layer thickness is between 30 and 60 nm. In one embodiment, thefinal layer thickness is between 60 and 90 nm. In one embodiment, thefinal layer thickness is between 90 and 120 nm. In one embodiment, thefinal layer thickness is between 120 and 150 nm. In one embodiment, thefinal layer thickness is between 150 and 280 nm. In one embodiment, thefinal layer thickness is between 180 and 200 nm.

In one embodiment, the photoactive layer comprises twoelectroluminescent materials, each of which is applied by thermalevaporation under vacuum. Any of the above listed vacuum conditions andtemperatures can be used. Any of the above listed deposition rates canbe used. The relative deposition rates can be from 50:1 to 1:50. In oneembodiment, the relative deposition rates are from 1:1 to 1:3. In oneembodiment, the relative deposition rates are from 1:3 to 1:5. In oneembodiment, the relative deposition rates are from 1:5 to 1:8. In oneembodiment, the relative deposition rates are from 1:8 to 1:10. In oneembodiment, the relative deposition rates are from 1:10 to 1:20. In oneembodiment, the relative deposition rates are from 1:20 to 1:30. In oneembodiment, the relative deposition rates are from 1:30 to 1:50. Thetotal thickness of the layer can be the same as that described above fora single-component photoactive layer.

In one embodiment, the photoactive layer comprises oneelectroluminescent material and at least one host material, each ofwhich is applied by thermal evaporation under vacuum. Any of the abovelisted vacuum conditions and temperatures can be used. Any of the abovelisted deposition rates can be used. The relative deposition rate ofelectroluminescent material to host can be from 1:1 to 1:99. In oneembodiment, the relative deposition rates are from 1:1 to 1:3. In oneembodiment, the relative deposition rates are from 1:3 to 1:5. In oneembodiment, the relative deposition rates are from 1:5 to 1:8. In oneembodiment, the relative deposition rates are from 1:8 to 1:10. In oneembodiment, the relative deposition rates are from 1:10 to 1:20. In oneembodiment, the relative deposition rates are from 1:20 to 1:30. In oneembodiment, the relative deposition rates are from 1:30 to 1:40. In oneembodiment, the relative deposition rates are from 1:40 to 1:50. In oneembodiment, the relative deposition rates are from 1:50 to 1:60. In oneembodiment, the relative deposition rates are from 1:60 to 1:70. In oneembodiment, the relative deposition rates are from 1:70 to 1:80. In oneembodiment, the relative deposition rates are from 1:80 to 1:90. In oneembodiment, the relative deposition rates are from 1:90 to 1:99. Thetotal thickness of the layer can be the same as that described above fora single-component photoactive layer.

In one embodiment, the electron transport layer is applied by vapordeposition. In one embodiment, it is deposited by thermal evaporationunder vacuum. In one embodiment, the vacuum is less than 10⁻⁶ torr. Inone embodiment, the vacuum is less than 10⁻⁷ torr. In one embodiment,the vacuum is less than 10⁻⁸ torr. In one embodiment, the material isheated to a temperature in the range of 100° C. to 400° C.; 150° C. to350° C. preferably. In one embodiment, the material is deposited at arate of 0.5 to 10 Å/sec. In one embodiment, the material is deposited ata rate of 0.5 to 1 Å/sec. In one embodiment, the material is depositedat a rate of 1 to 2 Å/sec. In one embodiment, the material is depositedat a rate of 2 to 3 Å/sec. In one embodiment, the material is depositedat a rate of 3 to 4 Å/sec. In one embodiment, the material is depositedat a rate of 4 to 5 Å/sec. In one embodiment, the material is depositedat a rate of 5 to 6 Å/sec. In one embodiment, the material is depositedat a rate of 6 to 7 Å/sec. In one embodiment, the material is depositedat a rate of 7 to 8 Å/sec. In one embodiment, the material is depositedat a rate of 8 to 9 Å/sec. In one embodiment, the material is depositedat a rate of 9 to 10 Å/sec. In one embodiment, the final layer thicknessis between 5 and 200 nm. In one embodiment, the final layer thickness isbetween 5 and 30 nm. In one embodiment, the final layer thickness isbetween 30 and 60 nm. In one embodiment, the final layer thickness isbetween 60 and 90 nm. In one embodiment, the final layer thickness isbetween 90 and 120 nm. In one embodiment, the final layer thickness isbetween 120 and 150 nm. In one embodiment, the final layer thickness isbetween 150 and 280 nm. In one embodiment, the final layer thickness isbetween 180 and 200 nm.

In one embodiment, the electron injection layer is applied by vapordeposition, as described above.

In one embodiment, the cathode is applied by vapor deposition, asdescribe above.

In one embodiment, the device is fabricated by vapor deposition of someof the organic layers, and liquid deposition of some of the organiclayers. In one embodiment, the device is fabricated by liquid depositionof the buffer layer, and vapor deposition of all of the other layers

Although methods and materials similar or equivalent to those describedherein can be used in the practice or testing of the present invention,suitable methods and materials are described below. In addition, thematerials, methods, and examples are illustrative only and not intendedto be limiting. All publications, patent applications, patents, andother references mentioned herein are incorporated by reference in theirentirety.

EXAMPLES

The concepts described herein will be further described in the followingexamples, which do not limit the scope of the invention described in theclaims.

Example 1

Example 1 demonstrates the preparation of a monomer having Formula I,shown as Compound 5 below.

Synthesis of Compound 2

Under an atmosphere of nitrogen, a 250 mL round bottom was charged with9,9-dioctyl-2,7-dibromofluorene (25.0 g, 45.58 mmol), phenylboronic acid(12.23 g, 100.28 mmol), Pd₂(dba)₃ (0.42 g, 0.46 mmol), P^(t)Bu₃ (0.22 g,1.09 mmol) and 100 mL toluene. The reaction mixture stirred for fiveminutes after which KF (8.74 g, 150.43 mmol) was added in two portionsand the resulting solution was stirred at room temperature overnight.The mixture was diluted with 500 mL THF and filtered through a plug ofsilica and celite and the volatiles were removed from the filtrate underreduced pressure. The yellow oil was purified by flash columnchromatography on silica gel using hexanes as eluent. The product wasobtained as a white solid in 80.0% (19.8 g). Analysis by NMR indicatedthe material to be compound 2 having structure given above.

Synthesis of Compound 3

A 250 mL three-necked-round-bottom-flask, equipped with a condenser anddripping funnel was flushed with N₂ for 30 minutes.9,9-dioctyl-2,7-diphenylfluorene (19.8 g, 36.48 mmol) was added anddissolved in 100 mL dichloromethane. The clear solution was cooled to−10° C. and a solution of bromine (12.24 g, 76.60 mmol) in 20 mLdichloromethane was added dropwise. The mixture was stirred for one hourat 0° C. and then allowed to warm to room temperature and stirredovernight. 100 mL of an aqueous 10% Na₂S₂O₃ solution was added and thereaction mixture was stirred for one hour. The organic layer wasextracted and the water layer was washed three times with 100 mLdichloromethane. The combined organic layers were dried with Na₂SO₄filtered and concentrated to dryness. Addition of acetone to theresulting oil gave a white precipitated. Upon filtration and drying awhite powder was obtained (13.3 g, 52.2%). Analysis by NMR indicated thematerial to be compound 3 having structure given above.

Synthesis of Compound 4

Under an atmosphere of nitrogen, a 250 mL round bottom was charged with3 (13.1 g, 18.70 mmol), aniline (3.66 g, 39.27 mmol), Pd₂(dba)₃ (0.34 g,0.37 mmol), P^(t)Bu₃ (0.15 g, 0.75 mmol) and 100 mL toluene. Thereaction mixture stirred for 10 min after which NaO^(t)Bu (3.68 g, 38.33mmol) was added and the reaction mixture was stirred at room temperaturefor one day. The resulting reaction mixture was diluted with 3 L tolueneand filtered through a plug of silica and celite. Upon evaporation ofvolatiles, the dark brown oil obtained was purified by flash columnchromatography on silica gel using a mixture of 1:10 ethylacetate:hexanes as eluent. The product was obtained as a pale yellowpowder in 50.2% (6.8 g). Analysis by NMR indicated the material to becompound 4 having structure given above.

Synthesis of Compound 5

In a 250 mL three-necked-round-bottom-flask equipped with condenser, 4(4.00 g, 5.52 mmol), 1-bromo-4-iodobenzene (4.68 g, 16.55 mmol),Pd₂(dba)₃ (0.30 g, 0.33 mmol) and DPPF (0.37 g, 0.66 mmol) were combinedwith 80 mL toluene. The resultant mixture was stirred for 10 min.NaO^(t)Bu (1.17 g, 12.14 mmol) was added and the mixture was heated to80° C. for four days. The resulting reaction mixture was diluted with 1L toluene and 1 L THF filtered through a plug of silica and celite toremove the insoluble salts. Upon evaporation of volatiles, the resultingbrown oil was purified by flash column chromatography on silica gelusing a mixture of 1:10 dichloromethane:hexanes as eluent. After dryinga yellow powder was obtained (4.8 g, 84.8%). Analysis by NMR indicatedthe material to be compound 5 having structure given above.

Example 2

Example 2 demonstrates the preparation of a copolymer of the monomerfrom Example 1 and a fluorene monomer having reactive styryl groupsusing Yamamoto polymerization.

Bis(1,5-Cyclooctadiene)-nickel-(0) (0.556 g, 2.02 mmol) was added to aN,N-dimethylformamide (anhydrous, 4 mL) solution 2,2′-bipyridyl (0.0.315g, 2.02 mmol) and 1,5-cyclooctadiene (0.219 g, 2.02 mmol). The resultingmixture was heated to 60° C. for 30 min. A toluene (anhydrous, 16 mL)solution of 2,7-dibromo-9,9′-(p-vinylbenzyl)-fluorene (0.0834 g, 0.15mmol) and compound 5 (0.88 g, 0.85 mmol), was then added rapidly to thestirring catalyst mixture. The mixture was stirred at 60° C. for sevenhours. After the reaction mixture cooled to room temperature, it waspoured, slowly, with vigorous stirring into 250 mL methanol and stirredovernight. Addition of 15 mL of conc. HCl followed and stirring for anhour. The precipitate was filtered and then added to 50 mL of tolueneand poured slowly into 500 mL of methanol. The resulting light-yellowprecipitate was stirred for one hour and then isolated by filtration.The solid was further purified by chromatography (silica, toluene) andprecipitation from ethyl acetate. After drying the resulting materialunder vacuum a light yellow polymer was isolated in 80% yield (0.64 g).GPC (THF, room temperature): Mn=80,147; Mw=262,659; Mw/Mn=2.98.

Example 3

This example illustrates the preparation of a homopolymer of the monomerfrom Example 1 using Yamamoto polymerization. 7

Bis(1,5-Cyclooctadiene)-nickel-(0) (0.833 g, 3.03 mmol) was added to aN,N-dimethylformamide (anhydrous, 6 mL) solution 2,2′-bipyridyl (0.473g, 3.03 mmol) and 1,5-cyclooctadiene (0.328 g, 3.03 mmol). The resultingmixture was heated to 60° C. for 30 min. A toluene (anhydrous, 24 mL)solution compound 5 (1.553 g, 1.50 mmol), was then added rapidly to thestirring catalyst mixture. The mixture was stirred at 60° C. for sevenhours. After the reaction mixture cooled to room temperature, it waspoured, slowly, with vigorous stirring into 250 mL methanol and stirredovernight. Addition of 15 mL of conc. HCl followed and stirring for anhour. The precipitate was filtered and then added to 50 mL of tolueneand poured slowly into 500 mL of methanol. The resulting light-yellowprecipitate was stirred for one hour and then isolated by filtration.The solid was further purified by chromatography (silica, toluene) andprecipitation from ethyl acetate. After drying the resulting materialunder vacuum a light yellow polymer was isolated in 82% yield (1.08 g).GPC (THF, room temperature): Mn=148,427; Mw=477,886; Mw/Mn=3.25.

Comparative Example A

This comparative example demonstrates the preparation of a copolymer ofa fluorene having distyryl groups and a triarylamine using Suzukipolymerization. A monomer having Formula I was not used.

N,N-Di-(4-bromophenyl)-N,N-diphenyl benzidine (0.488 g, 0.754 mmol),2,7-dibromo-9,9′-(p-vinylbenzyl)-fluorene (0.105 g, 0.189 mmol),9,9-dioctyl fluorene-2,7-diethyleneboronate (0.500 g, 0.943 mmol) weremixed into a 50 mL 2-neck round bottom flask. A condenser with N₂ gasadapter were added followed by Aliquat 336 (0.209 g, 0.518 mmol) intoluene (11.0 mL). The resulting mixture was degassed at roomtemperature. After degassing, a 0.002M solution oftetrakis-triphenylphosphine palladium (0) in toluene (2.0 mL, 0.004mmol) was injected and the solution further sparged for an additional 10minutes. The solution was then heated to 95° C. using an oil-bath. A2.0M sodium carbonate solution in water (2.8 mL, 5.657 mmol) wasinjected dropwise and the biphasic mixture vigorously stirred for 24hours. Phenylboronic acid (0.092 g, 0.754 mmol) was added as a degassedslurry in toluene (3.0 mL). Then a 0.002M solution oftetrakis-triphenylphosphine palladium (0) in toluene (1.5 mL, 0.004mmol) was injected and the reaction reheated to 95° C. overnight. Aftercooling, the aqueous and organic layers were separated and the organiclayer was washed 1× with 20 mL of water. Sodium diethyldithiocarbamate(0.25 g, 1.109 mmol) in water (20 mL) was added to the organic layer.The biphasic mixture was vigorously stirred at 80° C. overnight. Theaqueous and organic layers were separated and the organic layer washedwith water (3×20 mL), then 1× with 5% HCl (20 mL) and finally with water(3×20 mL). The organic layer was diluted with toluene (30 mL) andfiltered using a 1.5 cm (dia.)×8.0 cm (length) column loaded withAlumina-B (4 cm) layered on top of silica gel (4 cm). Toluene (90 mL)was used to elute the product. The pale yellow filtrate was precipitatedfrom methanol by reducing its volume to about 30 mL and adding itdropwise to stirring methanol (300 mL) at room temperature. The densepale yellow fibers were collected on a filter membrane (0.1 m Al₂O₃) andfurther dried under vacuum at room temperature for 1 hour. The fiberswere then redissolved in a larger volume of toluene (60 mL), to produceless dense fibers, and added dropwise to stirring methanol (600 mL) atroom temperature. The less dense fibers were collected on a filtermembrane (0.1 m Al₂O₃) and dried under vacuum at room temperature for 24hours. Isolated 0.708 g (87%) pale yellow fibers. GPC (THF, roomtemperature): Mn=42,067; Mw=172,727; Mw/Mn=4.10.

Example 4

This example demonstrates the performance of OLED devices made with holetransport polymer from Example 2 and with the hole transport polymerfrom Comparative Example A.

Patterned ITO substrates (device active area=2.24 mm×2.5 mm) werecleaned and cooled. A buffer layer at a thickness of about 180 nm wasspin-coated over the ITO surface. The buffer material layer was anaqueous dispersion of poly-pyrrole and a perfluorinated polymer, asdescribed in published U.S. patent application 2005-0205860. Thesubstrates were then baked and transferred to a drybox, in which allfurther manipulations were conducted. The substrates were spin-coatedwith a 0.4% w/v solution of a hole-transport material in toluene to forma hole-transport layer, and then baked again.

The substrates were spin-coated with a 1.5% w/v toluene solution of a13:1 w/w mixture of host:dopant supplied by Idemitsu Kosan Co. (Chiba,Japan) as listed in TABLE 1 to a thickness of 60-70 nm and baked at105-130° C. for 30 min at atmospheric pressure.

The substrates were then masked and placed in a vacuum chamber. A layerof tetrakis(8-hydroxyquinoline)zirconium (ZrQ) was deposited by thermalevaporation to form an electron transport layer. This was followed by alayer of lithium fluoride. An overcoat of Al was vapor deposited, toform the cathode. The devices were encapsulated using a glass lid,getter pack, and UV curable epoxy.

The devices were then measured for initial current, voltage, luminanceand color coordinate properties. Finally, the luminance degradationbehavior was examined by subjecting the devices to constant current fora prolonged time period while monitoring luminance and voltage change.The resulting device performance data is listed in Table 1. TABLE Curr.Lum. Life test Eff'cy Lum. CIE CIE ½ Lum. HTM [cd/A] Vlt. [cd/m²] [x][y] Life [h] [cd/m²] Example 2 4.4 5.1 426 0.133 0.148 1100 2245 pro-jected Comparative 4.4 5.8 371 0.134 0.156 215 2093 Ex. A

Note that not all of the activities described above in the generaldescription or the examples are required, that a portion of a specificactivity may not be required, and that one or more further activitiesmay be performed in addition to those described. Still further, theorder in which activities are listed are not necessarily the order inwhich they are performed.

In the foregoing specification, the concepts have been described withreference to specific embodiments. However, one of ordinary skill in theart appreciates that various modifications and changes can be madewithout departing from the scope of the invention as set forth in theclaims below. Accordingly, the specification and figures are to beregarded in an illustrative rather than a restrictive sense, and allsuch modifications are intended to be included within the scope ofinvention.

Benefits, other advantages, and solutions to problems have beendescribed above with regard to specific embodiments. However, thebenefits, advantages, solutions to problems, and any feature(s) that maycause any benefit, advantage, or solution to occur or become morepronounced are not to be construed as a critical, required, or essentialfeature of any or all the claims.

It is to be appreciated that certain features are, for clarity,described herein in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures that are, for brevity, described in the context of a singleembodiment, may also be provided separately or in any subcombination.Further, reference to values stated in ranges include each and everyvalue within that range.

1. A polymer made from at least one monomer having Formula I:

where: R and Y are independently selected from the group consisting ofH, D, alkyl, fluoroalkyl, aryl, fluoroaryl, alkoxy, aryloxy, NR″2, R′,

R′ is a crosslinkable group; R″ is independently selected from the groupconsisting of H, alkyl, fluoroalkyl, aryl, fluoroaryl, and R′; X thesame or different at each occurrence and is a leaving group; Z is C, N,or Si; Q is (ZR″_(n))_(b); a is an integer from 0 to 5; b is an integerfrom 0 to 20; c is an integer from 0 to 4; q is an integer from 0 to 7;and n is an integer from 1 to
 2. 2. A polymer of claim 1, wherein thepolymer comprises at least one comonomer selected from the groupconsisting of Formulae II through VIII:

where: R and Y are independently selected from the group consisting ofH, D, alkyl, fluoroalkyl, aryl, fluoroaryl, alkoxy, aryloxy, NR″₂, R′,

R′ is a crosslinkable group; R″ is independently selected from the groupconsisting of H, alkyl, fluoroalkyl, aryl, fluoroaryl, and R′; Q is(ZR″_(n))_(b); X can be the same or different at each occurrence and isa leaving group; Z is C, N, or Si; E is (ZR″_(n))_(b), O, S, Se, or Te;a is an integer from 0 to 5; b is an integer from 0 to 20; c is aninteger from 0 to 4; q is an integer from 0 to 7; and n is an integerfrom 1 to 2; with the proviso that the copolymer is made by Yamamotopolymerization.
 3. A polymer of claim 1 comprising a copolymer having aformula selected from Formulae X through XI:


4. A polymer of claim 1 comprising a copolymer having Formula XII:


5. A polymer of claim 1 which is a homopolymer.
 6. An electronic devicecomprising at least one polymer of claims 1 or
 2. 7. An electronicdevice comprising a photoactive layer comprising at least one polymer ofclaims 1 or
 2. 8. A device of claim 7 fabricated by liquid deposition ofthe photoactive layer.
 9. A device of claim 7 fabricated by vapordeposition or thermal evaporation deposition of the photoactive layer.10. A device of claim 6 also comprising an anode, a buffer layer, a holetransport layer, a photoactive layer, an electron transport layer, anelectron injection layer, and a cathode.
 11. A device of claim 10wherein the device is fabricated by liquid deposition of the buffer,hole transport and photoactive layers.
 12. A device of claim 10 whereinthe device is fabricated by vapor deposition of the electron transport,electron injection layers and the cathode.
 13. A device of claim 6comprising at least one hole transport material comprising at least oneof a (i) copolymer of a fluorene having distryryl groups and atriarylamine and (ii) a copolymer having Formula X.
 14. A device ofclaim 6 fabricated by liquid deposition of some organic layers and vapordeposition of some organic layers.